Wall box and ventilation system comprising a wall box

ABSTRACT

wherein K indicates an area of an enveloping circle with smallest possible radius, which circle completely conceals the cross section of the interior. The flap of the at least one flap arrangement has at least in an open position a flap contour which in regions adjacent to a pivot axis is adapted to a cross-sectional contour of the interior in the respective region adjacent to the pivot axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of German Patent Application Serial No. DE 10 2018 205 935.7 filed on Apr. 18, 2018, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference in its entirety as if fully set forth herein.

FIELD OF THE INVENTION

The invention relates to a wall box for a ventilation system and to a ventilation system comprising a wall box. The invention further relates to the arrangement of a wall box in an external wall of a building.

BACKGROUND OF THE INVENTION

Wall boxes are used in particular in the ventilation of kitchens by means of an extractor, or in controlled domestic ventilation. A wall box is known, for instance, from DE 10 2014 113 210 A1. Extractors for the extraction of cooking fumes are described, for example, in DE 20 2007 000 610 U1 and DE 20 2011 005 698 U1.

SUMMARY OF THE INVENTION

One object of the invention is to improve a wall box.

This object is achieved by a wall box for a ventilation system, comprising a housing delimiting an interior and having an inlet for an air stream and an outlet for an air stream, wherein a through-flow region connects the inlet and the outlet in a flow direction, and comprising at least one flap arrangement having a flap arranged on a suspension mounting, wherein the flap of the at least one flap arrangement is pivotable about a pivot axis defined by the suspension mounting between a closing position, which tightly closes off the through-flow region, and an open position, wherein, for an area A of a cross section of the interior perpendicular to the flow direction, A/K>2/π, wherein K indicates an area of an enveloping circle with smallest possible radius, which circle completely covers the cross section of the interior, wherein the flap of the at least one flap arrangement has at least in the open position a flap contour which in regions adjacent to the pivot axis is adapted to a cross-sectional contour of the interior in the respective regions adjacent to the pivot axis.

The wall box for a ventilation system has a housing delimiting an interior and having an inlet for an air stream and an outlet for an air stream. A through-flow region connects the inlet and the outlet in a flow direction. Moreover, the wall box has at least one flap arrangement having a flap arranged on a suspension mounting, wherein the flap of the at least one flap arrangement is pivotable about a pivot axis defined by the suspension mounting between a closing position, which tightly closes off the through-flow region, and an open position.

According to the invention, it has been recognized that a reduction of the flow resistance which the wall box, in the open position of the flap of the at least one flap arrangement, offers to an air stream, normally causes a disadvantageous enlargement of the external dimensions of the wall box. In the present wall box, a low flow resistance, combined, at the same time, with practicable external dimensions, is ensured by the following features: For an area A of a cross section of the interior perpendicular to the flow direction

A/K>2/π,   (1)

wherein K indicates an area of an enveloping circle with smallest possible radius, which circle completely covers the cross section of the interior. The flap of the at least one flap arrangement has at least in the open position a flap contour which, in regions adjacent to the pivot axis, is adapted to a cross-sectional contour of the interior in the respective regions adjacent to the pivot axis.

The invention relates, in particular, to the contouring of the flap, which, in combination with the cross-sectional contour, leads to synergy effects.

The wall box is intended for installation in a masonry wall. The masonry wall can in particular be an external wall of a building. The installation of the wall box in the masonry wall is realized such that the inlet and the outlet of the wall box are arranged on different sides of the masonry wall, in particular it can be provided to arrange the inlet on an inner side of the masonry wall and the outlet on an outer side of the masonry wall.

The flow direction is defined as the shortest connection from the inlet to the outlet. The flow direction is, in particular on a cross-sectional area of the inlet, vertical. If the wall box is installed horizontally, as intended, in the masonry wall, the flow direction is in particular horizontal, in particular parallel to a surface normal of the masonry wall.

As the through-flow region can be defined, in particular, a volume spanned by the cross-sectional area of the inlet and by a length of the wall box in the flow direction. The through-flow region has in particular the shape of a general cylinder, the cross section of which corresponds to the cross section of the inlet. In general, the through-flow region can in particular be equal to the smallest convex envelopes around the inlet and the outlet of the wall box and around the inlet and the smallest free flow cross-section in the interior of the wall box in the open position of the flap of the at least one flap arrangement. The through-flow region is a part of the interior of the wall box. In the open position of the flap, the air stream flows substantially only in the through-flow region.

The cross section of the interior can be constant or vary along the flow direction. In any event, the cross section fulfils the condition according to equation (1), wherein the precise value of A/K can vary. The enveloping circle completely covers the cross-sectional interior, wherein 1<A/K. The area K of the enveloping circle therefore constitutes an upper limit for the area A of the cross section of the interior. The area K of the circle thus constitutes the largest possible cross-sectional area for a given maximum diameter of the interior of the wall box. The condition

A/K=2/π≈0.6367

applies to a square cross section. The cross section of the interior deviates from a simple, substantially rectangular shape. For a given maximum diameter, the cross section has an area A which is enlarged in comparison to a rectangle. For a given maximum diameter of the interior which can correlate with maximum external dimensions of the wall box, a large area A of the cross section of the interior is ensured, which procures a better ventilation and a lower flow resistance. Preferredly, A/K>0.7, in particular A/K>0.8, in particular A/K>0.9, in particular A/K>0.95, in particular A/K>0.975.

An outer contour of the housing can deviate from the cross-sectional contour of the interior. Preferredly, however, the outer contour of the housing substantially corresponds to the cross-sectional contour of the interior. To this end, the housing can have along the periphery of a housing cross section a constant wall thickness. This ensures small external dimensions of the wall box related to the area A of the cross section of the interior. An outer contour of the housing that substantially corresponds to the cross-sectional contour of the interior has the advantage, moreover, that an area of a circle enveloping the outer contour of the housing is very largely filled. Suitable wall thicknesses lie, for instance, between 1 mm and 30 mm, measuring, in particular, at most 20 mm, in particular at most 10 mm, in particular at most 5 mm, preferredly around 2.5 mm.

A wall aperture which is necessary to the installation of the wall box in the masonry wall can thus be realized in a simple manner with a core drilling The wall box is assembly-friendly. Moreover, the wall box very largely fills a borehole cross section of the core hole, other than a box-shaped wall box. A wall aperture which is small in relation to the cross section of the interior which is available for the ventilation can therefore be provided. For instance, the diameter of the wall aperture exceeds the maximum diameter of the wall box maximally by 30%, in particular maximally by 25%, preferredly by maximally 20%, particularly preferredly by maximally 15%. The assembly of the wall box is simple and effective. A complex fitting of the wall box in the wall aperture is avoided. Moreover, the insulating complexity for the insulation of the wall aperture is reduced.

A cross section of the inlet can have any chosen shape. Preferredly, the shape of the cross section of the inlet corresponds to the shape of the cross section of a ventilation pipe to be connected to the wall box, for instance a ventilation duct, in particular a flat duct, or preferredly a round pipe. Particularly preferredly, the cross section of the inlet substantially corresponds to the cross section of the interior. Through an adaptation of the cross sections of the ventilation pipe, the inlet and the interior, turbulences in the air stream, in particular in the region of the inlet, are avoided. The fluid dynamics of the air stream in the wall box are improved.

The cross section of the outlet can deviate from the cross section of the inlet and/or the cross section of the interior. The cross section of the outlet can in particular be enlarged in relation to the cross section of the inlet. Preferredly, the cross sections of the outlet and of the inlet have the same shape. As a result, when the flap of the at least one flap arrangement is in the open position, the fluid dynamics of the air stream throughout the wall box are stabilized. Turbulences in the air stream along the flow direction, in particular in the region of the outlet, are reduced.

The at least one flap arrangement can comprise a plurality of flaps. In this case, the flaps of a flap arrangement can be arranged in particular side by side along a common pivot axis, or opposite to one another with respect to the cross section of the interior. Preferredly, however, the at least one flap arrangement has exactly one flap. This ensures an uncomplicated structure of the wall box. Moreover, the danger of catching when a plurality of flaps of the at least one flap arrangement are pivoted is avoided.

The flap of the at least one flap arrangement has a longitudinal direction. The longitudinal direction of the flap is defined as that direction perpendicular to the pivot axis in which the flap has the greatest extent measured perpendicular to the pivot axis. The longitudinal direction of the flap therefore corresponds to that greatest diameter of the flap running perpendicular to the pivot axis. Regardless of a pivot position of the flapper, the longitudinal direction runs perpendicular to the pivot axis. Moreover, the flap of the at least one flap arrangement has an orientation. The orientation is defined as the plane which is spanned by the longitudinal direction of the flap and of a straight line running parallel to the pivot axis. The orientation of the flap changes with the pivoting of the flap. The flap has in the closing position and in the open position different orientations.

In the closing position, the flap closes off the at least one flap arrangement and the through-flow region, in particular the whole of the interior of the housing, in a seal-tight, in particular gas-tight manner, in the region of the at least one flap arrangement. In the closing position, a direct air exchange between the inlet and the outlet is consequently prevented. In particular, in the closing position the direct air exchange between an outer side and an inner side of a building is prevented by the wall box. In particular an air stream counter to the flow direction, i.e. from the outlet to the inlet, is thus prevented. In the closing position, the orientation of the flap, and hence also the longitudinal direction thereof, can be substantially perpendicular to the flow direction.

In the open position of the flap, a fluid connection between the inlet and the outlet is given, so that an air stream can flow in the wall box in the flow direction. The air stream flows substantially through the through-flow region.

Due to the cross-sectional contour of the interior, which—as described above—deviates from a simple rectangular shape, a pivoting of the flap out of the closing position, in particular out of the through-flow region, is generally made more difficult. This is in particular the case if exactly one flap per flap arrangement is present. In the wall box according to the invention, this problem is solved by the, at least in the open position of the flap, defined flap contour, which, in regions adjacent to the pivot axis, is adapted to the cross-sectional contour of the interior in the corresponding regions adjacent to the pivot axis. The adaptation of the flap contour means that the external dimensions of the flap contour in the corresponding regions substantially correspond to the internal dimensions of the cross-sectional contour of the interior. “Substantially” should herein be understood to mean that, despite the adaptation of the external dimensions of the flap contour to the internal dimensions of the cross-sectional contour, there is enough play present that an, in particular frictionless, pivoting of the flap from the closing position into the open position, and back, is ensured.

The adaptation of the flap contour enables that the flap, even in an interior deviating from a rectangular cross section, can be easily pivoted from the closing position into the open position, and back. In particular, it is possible that the flap of the at least one flap arrangement in the open position is very largely swung out of the through-flow region. It is hereby prevented that the flap of the at least one flap arrangement in the open position ends up wholly, or to great extent, within the through-flow region. A flow resistance generated by the at least one flap arrangement, in particular the flap of the at least one flap arrangement, is reduced. This improves the fluid dynamics of the air stream in the wall box. Disturbing noises which the air stream generates as it flows around the flap of the at least one flap arrangement are reduced. The flow resistance of the wall box in the open position is further reduced.

Since the cross-sectional contour of the interior deviates from a simple rectangular shape, the flap of the at least one flap arrangement also has at least in the open position no simple flap contour, but rather a three-dimensional flap contour. At least in the open position, the flap of the at least one flap arrangement is, in particular, not flat or lamellar. Due to the three-dimensional flap contour, the flap has at least in the open position an extent in a contour direction. The contour direction runs perpendicular both to the longitudinal direction of the flap and to the pivot axis. The pivot axis, the longitudinal direction and the contour direction span an orthogonal coordinate system, with respect to which the contour and shape of the flaps can be measured. This coordinate system is fixed with respect to the respective flap and is pivoted with the flap. In the open position, the extent of the flap contour in the direction of the contour direction can amount to, for instance, at least 5%, in particular at least 10%, in particular at least 20%, in particular at least 30%, in particular at least 40%, preferredly at least 45%, of the maximum extent of the flap in the longitudinal direction.

For the adaptation of the flap contour in the open position, the flap of the at least one flap arrangement can be flexible or articulated. For instance, the flexibly or articulately designed flap, when pivoted into the open position, can be pressed, for instance, against the inner side of the housing, so that an adaptation of the flap contour to the cross-sectional contour of the interior is hereby realized. Alternatively, in particular in articulately designed flaps, an automatic pivoting of the flap parts one to another when pivoted into the open position can be realized. Preferredly, however, the flap is of rigid or dimensionally stable construction. This means that the flap is permanently contoured, i.e. regardless of a pivot position of the flap. This increases the stability and durability of the flap, and the reliability in respect of the opening and closing of the flap. The flap is also producible in a simple and favourable manner

Preferredly, the flap contour is adapted in such a way to the cross-sectional contour that the flap of the at least one flap arrangement bears in the closing position flush against the cross-sectional contour, in particular flush along the whole of the cross-sectional contour. The sealing effect of the closing position is thus ensured regardless of projections, sealing means and the like. The absence of projections against which the flaps could bear improves the flow characteristics. Moreover, no dirt can collect behind the projections. To this end, the flap can have two contour wings, which extend in the contour direction. In addition, contour edges, in particular rounded, can be configured on the flap, so that, despite sealing effect, there is sufficient play present that the flap can be pivoted in a simple, in particular frictionless, manner

In order to increase the sealing effect, the flap can have marginal sealing lips, in particular a circumferentially running sealing lip. The sealing lips are preferredly produced integrally with further parts of the flap, in particular a flap main body. The flap, in particular the flap main body, is particularly preferredly a dual-component part. In the manufacture of the flap, the sealing lips can be injection-moulded onto the flap main body.

Additionally or alternatively hereto, projections, in particular a projection which runs fully around the cross-sectional contour and against which the flap in the closing position bears, can be provided. The projections and/or the flap can have circumferential sealing lips in order to increase a sealing effect. In the case of a plurality of flap arrangements, a projection can respectively be provided for the respective flap.

According to one aspect of the invention, the cross-sectional contour of the interior has substantially the shape of a polygon, in particular of a regular polygon having at least five corners, or a circle. “Substantially” herein means that, for instance, the corners of the polygon can be rounded, and/or the edges thereof bulged. In relation to the circular form, this means, in particular, that the cross-sectional contour can have, for instance, flattened poles. In shape, the cross-sectional contour in the form of a circle corresponds to a cross-sectional contour in the form of a regular polygon having n corners, wherein n→∞. A cross-sectional contour of this type largely to completely fills the area of the enveloping circle. Cross-sectional contours of this type have proved particularly advantageous, since they correspond to conventional ventilation pipe cross-sectional contours. An optimized air conveyance from the ventilation pipe via the inlet through the interior up to the outlet is thus ensured. For instance, the ventilation pipe can be constructed as a round pipe having a diameter of 150 mm. In this case, the wall box can have a maximum external diameter of 180 mm, preferredly an external diameter of about 175 mm.

In the case of a round cross-sectional contour, the flap contour, at least in the open position of the flap, can have in regions adjacent to the pivot axis roundings, the radius of which is adapted to the radius of the cross-sectional contour. This can be ensured, in particular, by contour wings, which in a plane spanned by the pivot axis and the contour direction have the shape of circular arc segments.

According to a further aspect of the invention, the flap of the at least one flap arrangement is constructed in one piece. “In one piece” should herein be understood to mean that the flap is of integral configuration or consists of components rigidly connected to one another. For instance, the flap can be formed of various layers, such as a flap main body and an insulation layer fastened, in particular glued, hereon. The one-piece flap has, in particular, no various flap parts which are movable relative to one another. The one-piece flap, in particular a flap main body with integrally moulded-on sealing lip, completely covers in the closing position the cross section of the interior. A functional and simple closability of the interior is enabled by the flap. In particular, hinge joints and/or seals between individual flap parts can be dispensed with. Particularly preferredly, the flap of the at least one flap arrangement is of one-piece and dimensionally stable, that is to say permanently contoured, construction.

The pivoting of the flap of the at least one flap arrangement can be aided by motorized means. The motorized pivoting of the flap can, in particular, be coupled to the control device of a ventilation system, in particular of a fan or a blower.

According to a further aspect of the invention, the flap of the at least one flap arrangement is pivotable, purely mechanically, from the closing position into the open position. The use of a, for instance, electrical control system of the flap is herein avoided. This has the advantage of a simple and fall-safe working of the wall box. The wall box is distinguished by a currentless working. Fault-prone electric motors and/or tilting devices, in particular tilting devices between the electric motors and the flap, are not required.

The mechanical pivotability of the flap of the at least one flap arrangement can be realized, for instance, by springs disposed on the at least one flap arrangement, in particular by wrap springs or helical springs in the region of the suspension mountings. Preferably, the flap of the at least one flap arrangement is pivotable, however, purely passively. By this should be understood that the flap is pivotable out of the closing position solely on the basis of an air stream flowing in the flow direction. The flap is, in particular, pivotable without support by electrical and/or mechanical aids. This ensures a cost-effective design of the wall box, combined, at the same time, with high fail-safety.

In particular, it can be provided that the flap is pivotable out of the closing position only when a flow pressure of the air stream in the flow direction exceeds a predetermined opening pressure. It is hereby ensured that the flaps are not swung out of the closing position when the flow air stream in the flow direction is smaller than the flow pressure. In particular, the flaps can have the functionality of a non-return valve. It is hereby ensured that the wall box permits air streams only in the flow direction. An air stream counter to the flow direction is reliably prevented.

It has proved practicable if the opening pressure is between 60 Pa and 90 Pa, in particular between 65 Pa and 75 Pa. An unintended opening of the flaps is hereby avoided. The wall box fulfils the so-called “blower door test”, which calls for seal-tightness at an air draught of 60 Pa. At the same time, the maximum opening pressure of 90 Pa is low enough to avoid overloading of a preceding ventilation system, in particular a blower.

Particularly preferredly, the flap of the at least one flap arrangement is also pivotable from the open position into the closing position purely mechanically, in particular purely passively. This can be realized, for instance, by force of gravity.

In the closing position, the centre of gravity of the flap of the at least one flap arrangement can be displaced in relation to an area formed by the pivot axis and the gravitational direction. This can hence go hand in hand with the fact that the orientation of the flap of the at least one flap arrangement in the closing position is inclined by an angle in relation to a gravitational direction. This can be realized by virtue of the fact that the flap in the closing position bears against a projection. It is hereby ensured that the flap, solely on the basis of its own weight, remains in the closing position.

According to a further aspect of the invention, the pivot axis of the at least one flap arrangement is aligned horizontally and arranged in an upper half of the cross section. The upper half of the cross section is herein that half of the cross section which, if the wall box is installed as intended, lies with respect to the gravitational direction above the centroid of the cross section of the interior. Through such an arrangement of the pivot axis, a reverse pivoting of the flap of the at least one flap arrangement out of the open position into the closing position is possible solely on the basis of gravity.

This ensures a simple and reliable purely passive pivoting of the flap of the at least one flap arrangement from the open position into the closing position, in particular as soon as the flow pressure of an air stream falls below the opening pressure. Preferredly, the horizontally aligned pivot axis is arranged in the upper third of the cross section, particularly preferredly in the upper quarter of the cross section.

Preferredly, the flap of the at least one flap arrangement is balanced in relation to the pivot axis. This further increases the pivotability of the flap.

The balancing of the flap can be realized such that a centre of gravity of the flap with respect to the pivot axis has a lever arm which amounts to at most 25%, in particular at most 10%, in particular at most 1%, of an extent of the flap measured perpendicular to the respective pivot axis. It is hereby ensured that a pivoting of the flap is possible with a low torque. It can in particular be achieved that the flap is always pivoted into an open position with an orientation parallel to the flow direction when an air stream in the flow direction exceeds the opening pressure. The balancing can be procured, for example, by the arrangement of suitable counterweights in particular above the pivot axis.

According to a further aspect of the invention, the pivot axis of the at least one flap arrangement is arranged on an upper margin of the through-flow region or above this. A pivot axis arranged on the upper margin of the through-flow region or above this advantageously ensures that no constituent part of the associated flap arrangement that is found in the through-flow region is pivoted counter to the air stream. The air stream is not an obstacle to a simple pivoting about the pivot axis. This improves the functionality and dynamics of the at least one flap arrangement.

In particular in the case of a pivot axis arranged above the through-flow region, the corresponding suspension mounting is arranged outside the through-flow region. A negative influencing of the air stream by the suspension mounting of the at least one plate arrangement is avoided. It can hereby in particular be achieved that the flap of the at least one flap arrangement in the open position is for the most part or wholly swung out of the through-flow region. In contrast hereto, a pivot axis arranged within the cross section, in particular an arrangement of the pivot axis that evenly divides the cross section vertically or horizontally, is constantly found in the through-flow region. Such arrangements of the pivot axis have a substantially higher, disadvantageous flow resistance.

According to a further aspect of the invention, the flap of the at least one flap arrangement bears in the open position, in the region adjacent to the pivot axis, at least partially against the housing. The housing wall forms a stop for the flap in the open position. This enables a constructively particularly simple and stable suspension mounting of the flap in the open position. The orientation of the flap in the open position is fixed in particular parallel to the flow direction. The stop prevents fluttering of the flap in the open position. The open position is precisely defined by the stop.

According to a further aspect of the invention, at least two flap arrangements, which are spaced apart in the flow direction, are present.

There can also be provided more than two flap arrangements, which are spaced apart in the flow direction. In the closing position of the flaps of the at least two flap arrangements, an air cushion, which is defined by the spacing of the flap arrangements in the flow direction, is formed between the flaps. The air cushion procures a simple, cost-effective and reliable thermal insulation between the inlet and the outlet of the wall box. The air cushion ensures in particular a thermal insulation between the inner side and the outer side of the building. A thermal bridge between the inlet and the outlet is hereby avoided. In addition, the air cushion acts also as a sound insulation between the inlet and the outlet.

The various flap arrangements, in particular the flaps of the various flap arrangements, can be designed differently. For instance, only the flap of a flap arrangement can have a flap contour which at least in the open position is adapted to the cross-sectional contour of the interior. Preferredly, however, the flap arrangements and the flaps thereof are constructed in an equal manner Particularly preferredly, all flaps are pivotable purely mechanically, in particular purely passively, from the closing position into the open position, and back, and/or constructed in one piece. The above-stated features of the flap of the at least one flap arrangement are preferredly realized equally in all flaps.

Particularly preferredly, the flap of the at least one flap arrangement, in particular all flaps, is/are made of plastic. This enables a favourable production of the flaps. Moreover, the flaps are robust and have a low weight. As a result, the pivotability of the flaps is improved. The flap contour can be created with the known manufacturing processes for plastics parts in a simple and cost-effective manner with mass production means.

According to a further aspect of the invention, a spacing of the pivot axes of two adjacent flap arrangements is at least dimensioned such that the flaps of different flap arrangements in the open position have no overlap in the flow direction. In particular, an overlapping of adjacent flap arrangements in the open position can be avoided. A disadvantageous mutual abutment and/or catching of the flaps of two adjacent flap arrangements when pivoted from the closing position into the open position is hereby avoided. The pivotability of the flaps is not limited by an overlapping of the two flap arrangements.

It is in particular possible that the at least one flap of the flap arrangement that lies closest to the inlet in the flow direction is pivotable such that the orientation of the flap lies parallel to the flow direction. If the wall box is installed horizontally as intended, the orientation of a thus pivoted flap is aligned horizontally. Preferably, all flaps are pivotable in an orientation parallel to the flow direction. It can thereby in particular be achieved that all flaps in the open position are substantially swung out of the through-flow region. The air stream can flow without hindrance throughout the cross section of the through-flow region. A flow resistance which the flap arrangements offer to the air stream is minimized. As a result, the fluid dynamics of the air stream in the wall box are further improved.

A large spacing of adjacent flap arrangements further has the advantage of a large air cushion, so that the thermal insulation and the sound insulation of the wall box in the closing position are further improved.

Particularly preferredly, the spacing of the pivot axes of two adjacent flap arrangements is exactly dimensioned such that the flaps of different flap arrangements in the open position have no overlap, but also only a minimal spacing in the flow direction. This ensures the above-described advantages of mutually spaced flap arrangements, combined, at the same time, with small length of the wall box in the flow direction. Even in the case of small wall thickness, the wall box can be built in.

According to a further aspect of the invention, a flap arrangement, disposed adjacent to the outlet, of the at least one flap arrangement is arranged such that its flap in the open position protrudes from the outlet.

A flap, protruding from the outlet, of the flap arrangement disposed adjacent to the outlet forms in the open position a roof. In the open position, rain and/or dirt are thereby shielded from the outlet. Penetration of rain and/or dirt into the interior of the wall box is avoided, even with opened flaps. Preferredly, the flap of the flap arrangement disposed adjacent to the outlet is in the closing position arranged fully within the interior. An accumulation of dirt or moisture on the flap is in its closing position prevented. The flap is in its closing position, moreover, protected from wind.

A flap which in the open position protrudes from the wall box further reduces the length of this same which is required for the functionality of the wall box. The wall box can have a small length in the flow direction.

The suspension mounting of the at least one flap arrangement can be constructed as a sliding block guide. Alternatively, the suspension mounting of the at least one flap arrangement is configured as a ball bearing or slide bearing. Suspension mountings of this type set only a small friction against the pivoting of the flaps.

According to a further aspect of the invention, the suspension mounting of the at least one flap arrangement is constructed as a capsule-pin suspension mounting. Preferredly, the suspension mountings of all flap arrangements are constructed as capsule-pin suspension mountings. Capsule-pin suspension mountings are of simple design and cost-effective. Preferredly, the pin is constructed integrally with the flap on the sides thereof. The capsule can be constructed integrally with the housing, in particular as a bore in the housing. The suspension mounting is stable and ensures a precise and fall-safe pivoting of the flaps.

Preferredly, the suspension mounting of the at least one flap arrangement is made of brass or plastic, particularly preferredly of high-gloss polished brass or plastic. Particularly preferredly, all embodiments are made of plastic or brass. This ensures a stable suspension mounting. The suspension mounting can, in particular, be polished or high-gloss polished. This ensures a low friction in the pivoting of the plates. A capsule-pin suspension mounting made of polished, in particular high-gloss polished, plastic or brass ensures simple pivotability of the flaps, without, as in a ball bearing, for example, additional parts having to be provided. As a result, the functionality and fail-safety of the wall box is further improved. Moreover, a low production tolerance of the suspension mountings is ensured.

According to a further aspect of the invention, the flap of the at least one flap arrangement has an insulation layer. Preferredly, all flaps each have an insulation layer. The insulation layer further improves the thermal and/or acoustic insulation of the wall box. The insulation layer can in particular comprise a heat insulation material with low thermal conductivity. As the heat insulation material, expanded polystyrene (EPS), foamed plastic and/or fibrous materials, can, for instance, be used. In a particularly practicable embodiment of the flaps, the insulation layer is arranged in a seal-tight, in particular gas-tight, manner within the flaps. A contamination of the insulation layer, for instance fat droplets in the air flowing through the wall box, is hereby avoided. Alternatively, the insulation layer can also be applied to, in particular glued onto, the flaps, in particular to a flap main body. It can herein also be provided that the insulation layer is exchangeably applied to the plates. The flap consisting of flap main body and insulation layer glued hereon has a sandwich-like structure. In a further alternative, the insulation layer can also be realized by the flaps themselves being constructed as hollow bodies. In this case, the hollow body can be filled with air. Alternatively, the hollow body can also be evacuated. As a further alternative, a vacuum plate can be applied to, in particular glued onto, the flaps. In a particularly preferred alternative, the flaps themselves are made of an insulation material. This ensures a structurally simple, favourable and fall-safe design of the flap. Moreover, the weight of the flaps is reduced, which increases their pivotability.

Preferredly, the flaps have circumferential sealing lips, which in the closing position terminate flush with the cross-sectional contour. This further increases the seal-tightness and the insulating effect.

According to a further aspect of the invention, the wall box has a connecting socket in the region of the inlet for connection to a ventilation system. The connecting socket can in particular be constructed for connection to a ventilation pipe. Particularly advantageously, various connecting sockets detachably connected to the wall box can be provided. It is hereby ensured that different connecting sockets for various ventilation pipes are connectable to the wall box.

The housing is preferably made of plastic, in particular of heat-resistant plastic. In addition, the housing can be surrounded by an insulating material. In principle, it is also possible to produce the housing itself from the insulating material. The insulating material can comprise polystyrene. As a result of the insulating material, the configuration of a thermal bridge between the wall box and the masonry wall is avoided. The thermal insulation of the wall box is further improved. The insulating material can be present as an insulation block. The external shape of the insulation block can herein be chosen regardless of the shape of the housing. A positioning of the wall box in a masonry wall is hereby facilitated. For instance, the insulation block can also be exchangeable, so that the insulation block can be chosen in dependence on an opening in the masonry wall. The insulation block has in particular the function of an adapter between a wall aperture or wall opening and the housing of the wall box. For the installation of the wall box in the masonry wall, it can in particular be provided to initially insert just the insulation block into an opening in the masonry wall. Alternatively, the insulation block can also be directly encased with concrete. To this end, the insulation block can additionally comprise frangible or additional webs, which serve for this purpose and can be subsequently inserted. During the positioning and/or encasement of the insulation block, this is stabilized by the webs. Following the positioning and/or encasement of the insulation block, the webs, if need be, can be broken out and the housing inserted into the insulation block. The insulation block thus ensures a precise positioning and alignment of the housings in the wall aperture.

In addition, one or more means for fixing the flap of the at least one flap arrangement, in particular all flaps, in the closing position can be provided. These means can be constituted, in particular, by magnetic means.

The magnetic means can be disposed, for instance, on the flap and cooperate with a corresponding magnetic means which is arranged in the region of the housing wall. The magnetic means can be constructed as magnetic plates. Alternatively, one of the magnetic means can also be formed by a metallic surface. The magnetic means fix the flaps in the closing position and avoid a rattling and/or unwanted opening of the flaps in the closing position. Furthermore, the provision of the magnetic means has the advantage that an opening pressure required for the pivoting of the flaps can be precisely defined by the choice of magnetic means. Through the fixing of the flaps in the closing position, an intrusion of vermin through the wall box can additionally be prevented.

As particularly suitable magnetic means, permanent magnets have proved their worth. Alternatively hereto, the magnetic means can also comprise electromagnets.

Advantageously, an unlocking of the flaps can be coupled to the activity of a fan which generates the air stream. In this case, it can be ensured that the flaps are pivotable into the open position only in the event of an actively generated air stream. The means for fixing the flaps in the closing position, in particular the electromagnets, can be connected, in particular in a signal-transmitting manner, to the fan or a control device of this same.

In addition, in the floor of the interior can be formed a drain. As a result, liquid present in the interior, in particular water condensed from fumes transported with the air stream, can flow off from the interior. An adverse lasting effect of a liquid present in the wall box, for instance as a result of mould formation, is thus consequently prevented. For instance, the drain can be formed by the floor of the interior being inclined, at least in some areas, in relation to the horizontal in the direction of the outlet. The angle of inclination can in particular be between 0.5° and 2°, preferredly about 1°. Liquids can in this way flow by force of gravity along the inclination and run off through the outlet. An inclination of the floor can be obtained, for instance, by the entire housing being installed at an angle in relation to the horizontal. Alternatively, the inclination can also be procured by a widening of the housing in the direction of the flow direction. Alternatively or additionally hereto, the floor can also have a channel Preferredly, the channel, in the closing position of the flap of the at least one flap arrangement, is tightly sealed. This ensures impermeability of the wall box. A run-off of the liquid can then take place in the open position of the flap of the at least one flap arrangement.

It is a further object of the invention to improve a ventilation system.

This object is achieved by a ventilation system comprising a wall box according to the preceding description. The advantages correspond to those of the wall box.

The ventilation system can preferredly be an extractor system, in particular an extractor system for a kitchen. The ventilation system can comprise, in addition to the wall box, a fan and a ventilation pipe. It comprises, in particular, an extractor hood or a downward extractor, which is also referred to as a down-draught extractor. The fan can be constituted, for instance, by a ventilator, in particular a radial fan and/or axial fan. The ventilation pipe can be a round pipe. Preferredly, the ventilation pipe is constructed as a round pipe having a diameter of 150 mm Alternatively, the ventilation pipe is present as a ventilation duct, in particular as a flat duct.

A further object of the invention is to improve the arrangement of a wall box in an external wall of a building.

The object is achieved by the arrangement of the wall box according to the preceding description in an external wall of a building. The advantages derive from those of the wall box.

For the arrangement of the wall box in the external wall of the building, it is in particular provided to perform a core drilling through the external wall. The diameter of the core hole is preferably maximally 30 percent, in particular maximally 20 percent, in particular maximally 10 percent, preferredly maximally 5%, particularly preferredly maximally 2.5% greater than the maximum external diameter of the wall box. The installation of the wall box, and in particular the insulation of this same, are hereby improved. For instance, a wall box having an external diameter of the housing of 175 mm can have with the insulation layer an external diameter of 180 mm in total and can be inserted into a corresponding core hole.

Further details, advantages and features of the invention emerge from the description of an illustrative embodiment with reference to the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic representation of a ventilation system comprising a wall box arranged in an external wall,

FIG. 2 shows a perspective view of an illustrative embodiment of a wall box, wherein flaps of the wall box are represented in a closing position,

FIG. 3 shows a cross section through the wall box according to FIG. 2,

FIG. 4 shows a horizontal longitudinal section through the wall box along a section edge IV-IV in FIG. 3,

FIG. 5 shows a vertical longitudinal section through the wall box along a section edge V-V in FIG. 3,

FIG. 6 shows a perspective view of the wall box according to FIG. 2, wherein the flaps are represented in an open position,

FIG. 7 shows a cross section through the wall box according to FIG. 6,

FIG. 8 shows a side view of the wall box according to FIG. 6,

FIG. 9 shows a vertical longitudinal section through the wall box along a section edge IX-IX in FIG. 7, and

FIG. 10 shows a perspective view of a flap for the wall box according to FIGS. 2 to 9.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, a ventilation system 1 is shown in schematic representation. The ventilation system 1 serves to ventilate a living area 2 of a building into an environment 3 surrounding the building. To this end, the ventilation system 1 has a wall box 5 arranged in an external wall 4 of the building.

The living area 2 can be, for instance, a kitchen or a kitchen-diner. The ventilation system 1 is an extractor system for the extraction of cooking fumes. It comprises an intake opening 6 for the cooking fumes which are to be drawn off The intake opening 6 is configured as a downward extractor, which is also referred to as a down-draught extractor. The intake opening 6 is fluidically connected to a fan 7. The fan 7 generates the air stream required for the extraction of the cooking fumes. The fan 7 is constructed as a ventilator, in particular as a radial fan. Following the fan 7 is arranged a ventilation pipe 8. The ventilation pipe 8 provides a fluid connection between the fan 7 and the wall box 5. The air sucked up from the living area 2 through the intake opening 6 with the aid of the fan 7, and the cooking fumes contained therein, are conducted via the ventilation pipe 8 and the wall box 5 into the environment 3.

With reference to FIGS. 2 to 10, an illustrative embodiment of the wall box 5 is described in detail below. The wall box 5 has a housing 10 delimiting an interior 9. The housing 10 has an inlet 11 for an air stream and an outlet 12 for an air stream. In the region of the inlet 11 is arranged a connecting socket 13. Via the connecting socket 13, the ventilation pipe 8 is connected in a fluid-tight manner to the wall box 5. The connecting socket 13 is detachably connected to the housing 10, so that, depending on the design of the ventilation pipe 8, various connecting sockets 13 can be connected to the wall box. The connecting socket 13 serves as an adapter for the connection of the ventilation pipe 8.

In the represented illustrative embodiment, the connecting socket for a ventilation pipe 8 constructed as a round pipe is designed with a diameter of 150 mm. A diameter 14 and cross section of the inlet 11 (see FIG. 4, 5, 7 or 9) correspond to the diameter and cross section of the ventilation pipe 8. The diameter 14 of the inlet 11 is thus 150 mm The inlet 11 has a circular cross section. The housing 10 is substantially circular-cylindrical. It has a maximum external diameter of 175 mm.

The housing 10 is made of heat-resistant plastic. It has a constant wall thickness between 0.1 mm and 10 mm, in particular of about 2.5 mm. Due to the constant wall thickness, the interior 9 also has the shape of a regular cylinder of circular cross section. A cross-sectional contour 16 of the interior 9 therefore corresponds to the circumferential line of a circle having a cross-sectional diameter 17 (see FIG. 7). An area A of the cross section of the interior 9 therefore corresponds to the area of the circle with diameter 17 and circumference 16. As a result of this design of the interior 9, an optimal utilization of the space occupied by the wall box within a masonry wall of the external wall 4 is created. In particular, the cross section of the interior 9 is maximized with respect to the external dimensions of the wall box 5, in particular its external diameter.

In a non-represented alternative, onto the inner side of the housing 10 are formed projections, against which the flaps 23 bear in their closing position. As a result of the projections, the closing position is precisely defined. Moreover, via the projections, in particular via sealing lips arranged on the projections or the flaps 23, the insulation in the closing position of the flaps 23 is improved once again. The projections can be shaped from solid material or in the form of an undercut. Alternatively, the flaps 23 can be pivotably mounted in the region of a widened cross section of the interior 9.

In that arrangement of the wall box 5 in the external wall 4 of the building that is shown in FIG. 1, the inlet 11 with the connecting socket 13 is arranged on an inner side of the external wall 4 that is facing towards the living area 2, and the outlet 12 is arranged on an outer side of the external wall 4 that is facing towards the environment 3. If installed as intended, the wall box 5 is aligned horizontally. This means that a centre axis of the circular-cylindrical housing 10 runs parallel to a surface normal 15 of the external wall 4. Due to the circular-cylindrically configured housing 10 of the wall box 5, its arrangement in a masonry wall of the external wall 4 is simplified. A wall aperture necessary for the insertion of the wall box 5 into the external wall 4 can be realized in a simple manner by a core drilling with circular drilling cross section. The diameter of the core hole can be adapted to the external diameter of the wall box 5. The provision of a square wall aperture or of partially overlapping core holes, as is necessary for the insertion of a, for instance, square wall box, is avoided. Particularly preferredly, the wall box 5 is arranged in a core hole of greater diameter. In the interspace between the wall box 5 and the internal diameter of the core hole is then arranged an insulating material. As a result of the insulating material, the formation of a thermal bridge between the wall box 5 and the masonry wall of the external wall 4 is avoided. This ensures a good thermal insulation of the wall box 5.

Within the interior 9 of the wall box 5 is defined a through-flow region 18. The through-flow region 18 connects the inlet 11 to the outlet 12 in a flow direction 19 (see FIG. 4, 5, 7 or 9). The flow direction 19 is defined as the shortest connection from the inlet 11 to the outlet 12. Where the interior 9 is configured as a regular cylinder, the flow direction 19 stands perpendicularly on the cross-sectional area of the inlet 11 and the cross-sectional area of the outlet 12. If the wall box 5 is installed horizontally as intended, the flow direction 19 is aligned horizontally. The flow direction 19 is thus parallel both to the centre axis of the cylindrical housing 10 and to the surface normal 15 of the external wall 4.

The through-flow region 18 is defined as a volume which is spanned by the length of the wall box 5 in the flow direction 19 and the cross-sectional area of the inlet 11. The through-flow region 18 is therefore a cylindrical volume having a cross-sectional area corresponding to the cross-sectional area of the inlet. The cross-sectional area of the through-flow region 18 therefore also corresponds to the cross-sectional area of the ventilation pipe 8. Turbulences are hereby effectively avoided.

In addition, the wall box 5 has an inlet-side flap arrangement 20 and an outlet-side flap arrangement 21. The flap arrangements 20, 21 are of same construction. They respectively comprise exactly one flap 23 arranged on a suspension mounting 22.

The flaps 23 are in one piece and dimensionally stable. They respectively have a flap main body (not shown explicitly) made of plastic. Moreover, the flaps 23 respectively have an insulation layer (not represented explicitly). The insulation layer is glued as an insulating material, for instance foamed plastic or expanded polystyrene, on the flow-facing side of the flaps 23, i.e. in their closing position on the side facing towards the inlet 11, onto the flap main body. In non-represented alternatives, the insulation layer is integrated into the flaps 23. In further non-represented alternatives of the flaps 23, the insulation layer can also be realized as a vacuum or air pocket within the flaps 23. In yet other alternatives, the flaps 23 themselves are made of insulating material. In some alternatives, the flaps 23 each have a circumferential sealing lip. The sealing lip is injection-moulded as a soft component onto the flap main body. The flap-main body is a dual-component part.

The suspension mountings 22 are realized as capsule-pin suspension mountings. The capsules 24 are constructed as bores in the housing 10. The pins 25 are shaped integrally with the flaps 23 (cf. in particular FIG. 10). The pins 25 and the capsules 24 are high-gloss polished, whereby a friction between the pins 25 and the capsules 24 is reduced. The suspension mountings 22 enable simple pivoting of the flaps 23 about a pivot axis 26 defined by the respective suspension mounting 22. The pivot axes 26 are arranged perpendicular to the flow direction 19 and above the through-flow region 18.

The flaps 23 respectively have a longitudinal direction 27. The longitudinal direction 27 is defined as that direction perpendicular to the pivot axis 26 in which the flap has the greatest extent. Regardless of a pivot position of the respective flap 23, the longitudinal direction 27 runs perpendicular to the pivot axis 26. The plane spanned from the pivot axis 26 and the longitudinal direction 27 defines an orientation of the flap 23. When the flap 23 is pivoted about the pivot axis 26, the orientation of the flap 23 changes.

Moreover, the flaps 23 have a contour direction 28. The contour direction 28 runs perpendicular to the pivot axis 26 and to the longitudinal direction 27. The pivot axis 26, the longitudinal direction 27 and the contour direction 28 span an orthogonal coordinate system, with respect to which the contour and shape of the flaps 23 is fixed. This coordinate system is fixed with respect to the respective flap 23 and is pivoted with the flap 23. If the wall box 5 is installed as intended, the pivot axis 26 runs horizontally.

The flaps 23 have a flap contour 29, which is determined substantially by the extent of the flap 23 in the directions defined by the pivot axis 26, the longitudinal direction 27 and the contour direction 28. The flap contour 29 is described in detail below in connection with the pivotability of the flaps 23.

The flaps 23 are pivotable about the pivot axis 26 between a closing position shown in FIGS. 2 to 5 and an open position shown in FIGS. 6 to 9.

In the closing position, an orientation of the flaps 23 is parallel to the cross-sectional area of the inlet 11 or of the outlet 12. If the wall box 5 is installed horizontally, as intended, in the external wall 4, the longitudinal direction 27 of the flaps 23 in the closing position runs parallel to a gravitational direction. The contour direction 28 of the flaps 23 runs in the closing position parallel to the flow direction 19.

In the closing position, the flaps 23 close off the whole of the interior 9, and hence the through-flow region 18, in a gas-tight manner In the closing position of the flaps 23, a fluid connection between the inlet 11 and the outlet 12 is interrupted. It is hereby in particular ensured that, from the outlet 12, no air stream can flow in the direction of the inlet 11. The intrusion of ambient air into the living area 2 is in the closing position of the flaps 23 consequently prevented. In the closing position, an air cushion 30 is realized between the flap arrangements 20, 21 (see FIGS. 4 and 5).

The pivot axes 26 of the flap arrangements 20, 21 have in the flow direction 19 a spacing 34 which is greater than a maximum extent of the flaps 23 in the longitudinal direction 27 (cf. FIGS. 5, 8 and 9). Due to the prevented air exchange, in the closing position of the flaps 23 is formed between the flap arrangements 20, 21 an air cushion 30, the extent of which substantially corresponds to the spacing 34 of the pivot axes 26 of the flap arrangements 20, 21 in the flow direction 19. The air cushion 30 procures a simple and reliable insulation between the inlet 11 and the outlet 12 of the masonry wall 5. A thermal insulation and a sound insulation between inner side and outer side of the external wall 4 of the building is hereby ensured.

The insulation of the wall box 5 is procured in the closing position by the insulation layer of the flaps 23 and the air cushion 30.

In the open position, the flaps 23 are pivoted in the flow direction 19. In the open position, the orientation of the flaps 23 is perpendicular to a gravitational direction. This means that the longitudinal direction 27 of the flaps 23 runs parallel to the flow direction 19. Correspondingly, the contour direction 28 is parallel to the gravitational direction.

In the open position, the flaps 23 are pivoted such that a fluid connection between the inlet 11 and the outlet 12 is created. In the open position of the flaps 23, an air stream 33 (see FIG. 9) can flow from the inlet 11 along the flow direction 19 via the through-flow region 18 through to the outlet 12. The air stream 33 herein flows substantially within the through-flow region 18. In the open position, the flaps 23 substantially fully open up the through-flow region. The flap arrangements 20, 21 and their respective flaps 23 are swung out of the through-flow region 18 and generate no flow resistance against the air stream 33 flowing in the direction of the flow direction 19 from the inlet 11 to the outlet 12. Due to the spacing 34 of the pivot axes 26 of the flap arrangements 20, 21, it is ensured that the flaps 23 in the open position do not overlap. A catching of the flaps 23 when swung out of the closing position into the open position or out of the open position into the closing position is avoided. In particular, the outlet-side flap arrangement 21 does not prevent a full pivoting of the inlet-side flap arrangement 21.

The flap contour 29 enables the flaps 23 constructed in one piece to be pivoted out of the through-flow region 18 and, at the same time, enables a gas-tight closure of the interior 9 in the closing position. To this end, the flap contour 29 is adapted to the cross-sectional contour 16 of the interior 9. This is realized by virtue of the fact that the maximum extent of the flaps 23 is adapted, both in the longitudinal direction 27 and in a direction parallel to the pivot axis 26, respectively to the cross-sectional diameter 17 of the interior 9. Moreover, a projection of the flap contour 29 onto a plane formed from the pivot axis 26 and the longitudinal direction 27 has a circular shape (cf. FIG. 3). In the closing position, the flap contour 29 bears along the whole of the cross-sectional contour 16 of the interior 9 flush against the housing 10. As a result, the closing position is precisely defined and a rattling of the flaps 23 in the closing position prevented.

Moreover, the flap contour 29 extends, in regions adjacent to the pivot axis 26, along the contour direction 28. In these regions adjacent to the pivot axis 26, the flap contour 29, along the contour direction 28, is adapted to the cross-sectional contour 16 of the interior in the corresponding regions adjacent to the pivot axis 26. This is realized by virtue of the fact that the flaps 23 respectively have two contour wings 31. The contour wings 31 are arranged, in the direction of the pivot axis 26, laterally to the pins 25. In a plane spanned by the pivot axis 26 and the contour direction 28, the contour wings 31 have the shape of circular arc segments (cf. FIGS. 4 and 7).

The radius of the circular arcs described by the contour wings 31 is dimensioned such that the contour wings 31 in the open position bear flush against regions of the housing 10 which lie adjacent to the pivot axis 26. This means that the radius of the circular arcs described by the contour wings 31 substantially corresponds to the radius of the cross-sectional contour 16. The housing 10 forms a stop for the contour wings 31, and hence for the flaps 23 in the open position. The open position of the flaps 23 is thus precisely fixed. A fluttering and/or rattling of the flaps 23 in the open position is prevented. The contour wings 31 have in the contour direction 28 an extent which is greater than 40% of the maximum extent of the flaps 23 in the longitudinal direction 27.

Moreover, the flaps 23 have circumferential contour edges 32 (cf. FIGS. 6, 8 and 10). The contour edges 32 are rounded such that a frictionless pivoting of the flaps 23 from the closing position into the open position, and back, is ensured.

In the closing position shown in FIGS. 2 to 5, the flap 23 of the outlet-side flap arrangement 21 is arranged fully within the interior 9, that is to say fully within the housing 10. In the open position shown in FIGS. 6 to 9, the flap 23 of the outside flap arrangement 21 projects beyond the outlet 12 of the housing 10. By the flap 23 of the outside flap arrangement 21 is therefore formed, in the open position, a roof which shields the outlet 12. In the open position of the flaps 23, rainwater is thus also prevented from being able to intrude via the outlet 12 into the interior 9 of the wall box 5.

Below, the mechanism for the pivoting of the flaps 23 is described. The flaps 23 pivot purely passively. No electric motors and other active actuating mechanisms for the pivoting of the flaps 23 are therefore provided. The flaps 23 pivot solely on the basis of the air stream 33 generated by the fan 7. The flaps 23 are always in the closing position when no air stream 33 is flowing or a flow pressure of the air stream 33 is lower than a predetermined opening pressure. As soon as the flow pressure of the air stream 33 exceeds the predetermined opening pressure, the flaps 23 pivot out of the closing position into the open position. If the flow pressure of the air stream 33 falls below the opening pressure, the air stream 33 completely subsides, or even an air stream flows counter to the flow direction 19, and the flaps, by force of gravity, pivot purely passively out of the open position into the closing position. The flaps 23 have the function of a non-return valve, so that an air stream from the outlet 12 to the inlet 11 procures a closure of the flaps 23. An air stream counter to the flow direction 19 is thus not possible.

A practicable opening pressure lies between 15 Pa and 90 Pa, in particular between 50 Pa and 60 Pa. This ensures that an unintended opening of the flaps 23 is avoided. At the same time, an overloading of the fan 7 is avoided.

The pivotability of the flaps 23 is ensured by their low own weight and the low friction realized by the high-gloss polished capsule-pin suspension mounting 22. This enables a pivoting of the flaps 23 with a low torque. Moreover, it is ensured that the flaps 23, even in the event of a flow pressure of the air stream 33 which only slightly exceeds the opening pressure, are pivoted from the closing position fully into the open position.

In further alternatives of the wall box, the pivoting of the flaps can additionally be aided by a balancing of the flaps 23 with respect to the pivot axes 26. The balancing of the flaps 23 is realized such that a centre of gravity of the flaps 23 has with respect to the respective pivot axis 26 a lever arm which amounts to at most 25%, in particular at most 10%, in particular at most 1%, of an extent of the flaps 23 measured along the longitudinal direction 27. This can be accomplished, for instance, by the provision of counterweights above the suspension mountings 22.

In further non-represented alternatives of the wall box, the housing has the shape of a regular cylinder having a non-circular base area. For instance, the base area is a regular polygon having 5 or more corners. Oval base areas or polygons having rounded edges and corners can also be realized. The housing can also have a cross section which varies along the flow direction. In all alternatives, for an area A of the cross section of the interior perpendicular to the flow direction, however:

A/K>2/π,

wherein K indicates an area of an enveloping circle with smallest possible radius, which circle completely covers the cross section of the interior.

In further non-represented alternatives, the flaps, at least in the region of the contour wings, are flexible. This means that the flaps in the closing position can be lamellar and in the open position are deformed by the fact that they bear against the housing, so that the flap contour is adapted to the cross-sectional contour. In yet other alternatives, contour wings are articulately connected to the rest of the flap. 

What is claimed is:
 1. 1. A wall box (5) for a ventilation system (1), comprising 1.1 a housing (10) delimiting an interior (9) and having 1.1.1. an inlet (11) for an air stream and 1.1.2. an outlet (12) for an air stream, 1.1.3. wherein a through-flow region (18) connects the inlet (11) and the outlet (12) in a flow direction (19), and comprising 1.2. at least one flap arrangement (20, 21) having a flap (23) arranged on a suspension mounting (22), 1.3. wherein the flap (23) of the at least one flap arrangement (20, 21) is pivotable about a pivot axis (26) defined by the suspension mounting (22) between a closing position, which tightly closes off the through-flow region (18), and an open position, 1.4. wherein, for an area A of a cross section of the interior (9) perpendicular to the flow direction (19) A/K>2/π, wherein K indicates an area of an enveloping circle with smallest possible radius, which circle completely covers the cross section of the interior (9), 1.5. wherein the flap (23) of the at least one flap arrangement (20, 21) has at least in the open position a flap contour (29) which in regions adjacent to the pivot axis (26) is adapted to a cross-sectional contour (16) of the interior (9) in the respective regions adjacent to the pivot axis (26).
 2. The wall box (5) according to claim 1, wherein the cross section of the interior (9) has substantially the shape of one of the group comprising a polygon having at least five corners and a circle.
 3. The wall box (5) according to claim 1, wherein the flap (23) of the at least one flap arrangement (20, 21) is constructed in one piece.
 4. The wall box (5) according to claim 1, wherein the flap (23) of the at least one flap arrangement (20, 21) is pivotable, purely mechanically, from the closing position into the open position.
 5. The wall box (5) according to claim 1, wherein the pivot axis (26) of the at least one flap arrangement (20, 21) is aligned horizontally and arranged in an upper half of the cross section of the interior (9).
 6. The wall box (5) according to claim 5, wherein the pivot axis (26) of the at least one flap arrangement (20, 21) is arranged on one of the group comprising an upper margin of the through-flow region (18) and above this.
 7. The wall box (5) according to claim 1, wherein the flap (23) of the at least one flap arrangement (20, 21) bears in the open position, in the regions adjacent to the pivot axis (26), at least partially against the housing (10).
 8. The wall box (5) according to claim 1, comprising at least two flap arrangements (20, 21), which are spaced apart in the flow direction (19).
 9. The wall box (5) according to claim 8, wherein a spacing of the pivot axes (26) of two adjacent flap arrangements (20, 21) is at least dimensioned such that the flaps (23) of different flap arrangements (20, 21) in the open position have no overlap in the flow direction (19).
 10. The wall box (5) according to claim 1, wherein a flap arrangement (21), disposed adjacent to the outlet (12), of the at least one flap arrangement (20, 21) is arranged such that its flap (23) in the open position protrudes from the outlet (12).
 11. The wall box (5) according to claim 1, wherein the suspension mounting (22) of the at least one flap arrangement (20, 21) is constructed as a capsule-pin suspension mounting.
 12. The wall box (5) according to claim 1, wherein the flap (23) of the at least one flap arrangement (20, 21) has an insulation layer.
 13. The wall box (5) according to claim 1, comprising a connecting socket (13) in the region of the inlet (11) for connection to a ventilation system (1).
 14. A ventilation system (1) comprising a wall box (5) according to claim
 1. 15. An arrangement of a wall box (5) according to claim 1 in an external wall (4) of a building. 